By the end of 1940 the I.A.R. biplanes were in large-scale service with Fortelor Aeriene Regal ale Romania (Royal Romanian Air Force) or FARR. They equipped a number of squadrons attached to the various army corps and by June 1941, when Romania supported the German offensive against the Soviet Union, the three reconnaissance flotile of the FARR had 18 eskadrile, 15 of which were equipped with I.A.R. biplanes.
In July 1942 the air expeditionary force in the Soviet Union had been re-formed as Corpul I Aerian and had several groups equipped with the I.A.R.39. Eleven reconnaissance eskadrile were operating with the army co-operation flotile during the 1944 offensive in the Ukraine, most of them with I.A.R.39s on strength.
Post-war the new Communist republic was declared at the end of 1947, and the reorganised air arm, known as the FR-RPR (Fortele Aeriene ale Republicii Populare Romania) had a small number of I.A.R.39s for training and liaison duties for several years.
